David Hughes is the Daily Telegraph's chief leader writer. He has been covering British politics for 30 years.

James Murdoch is a sideshow – it's Rupert who is feeling the heat

When James Murdoch stood down as executive chairman of News International in February, it seemed unlikely that this attempt to draw a line beneath the phone-hacking scandal was going to work. And so it has proved. Murdoch Junior’s resignation today as chairman of BSkyB – though it seems he will stay on the board – is another attempt to throw ballast out of a sinking balloon. In fact, the serial resignations of the younger Murdoch look increasingly like a sideshow. It is Murdoch Senior who is now finding himself in the firing line. Last month BBC’s Panorama alleged that a Murdoch company called NDS launched a dirty tricks campaign against the rival ITV Digital that led ultimately to its being forced out of business. Last week, the Australian Financial Review carried similar allegations about News Corporation’s activities in Australia. It said News Corp had a secret unit called Operational Security – set up in the mid-1990s – with the specific aim of sabotaging its competitors. In corporate terms, these latest allegations make the phone-hacking scandal look like small potatoes. News Corporation’s shareholders must be looking long and hard at them and wondering if there’s any more dirt still to come out. Meanwhile, both the Murdochs are due to testify before Lord Justice Leveson’s inquiry later this month. Should be interesting.